Re: [Tarantool-patches] [PATCH v4 0/6] box/func: implement cfunc Lua module

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Hi! Thanks for the patchset!

On 01.10.2020 15:51, Cyrill Gorcunov wrote:
> The cfunc module provide a way to execute C stored procedures
> on read only nodes without registring them in `_func` system space.
> 
> The series implements a bare minimum. There was a request to make
> cfunc been Lua object with appropriate methods. If this is really
> preferred then I'll implement this wrapping Lua code on top. I mean
> that currently all operations are done via
> 
>  > require('cfunc').[create|drop|call|reload]
> 
> interface while there was a proposal to operate as
> 
>  > a = require('cfunc').create
>  > a:call(args)

No, the proposal was rather

	cfunc = require('cfunc')
	f = cfunc.load('test_box_c_function')
	f(1, 2, 3)

Sorry I didn't describe it properly anywhere. But it is easy to fix
anyway.

In Lua you can define __call and make an object look exactly
like a function. That is the idea behind making it possible to
use Lua and C functions in the same way.

	if load_c then
		f = cfunc.load('test_box_c_function')
	else
		f = function(a, b, c) return a + b + c end
	end
	f(1, 2, 3) -- Works and looks the same for C and Lua.

With this way even IPROTO_CALL should work on such functions, if the
function object is global and the user has access to executing everything
here.